Digitizers are utilized in the art in the manufacture of orthotic and prosthetic devices such as artificial limbs and braces. Such digitizers are used for sending positional reference points of a three dimensional shape to the computer aided design and manufacturing (CAD/CAM) systems. In such practice the shape of the residual limb of the amputee, for example, is converted into a series of data points from which a computer can construct a three dimensional model of the residual limb. Digitizers are the instruments used to perform this shaped measurement function. In practice the prosthetist uses a marking pen to draw or mark certain important anatomical features on the residual limb which are later used when designing the proper socket shape. These marks indicate areas of irregularity, such as scar tissue or standard anatomical features as other reference points on the residual limb. A plaster cast would be made around the residual limb with the cast being the reverse or female model of the residual limb and with the marks denoting the important reference points. The marks are transferred to the inner surface of the plaster cast. A known digitizer includes a movable pendent arm having a contact wheel at its free end for making rolling contact with the inner surface of the cast. Prior contact wheel digitizers require constant attendance by a prosthetist to assure the proper capturing of the visibly marked positional reference points.
Traditional, labor intensive techniques for designing and fabricating an artificial limb typically require between 15-40 hours of direct labor input by a prosthetist and a fabrication technician. The largest portion of this time (upwards of 50%) is spent creating the socket portion of the limb--the precisely shaped hollow area in the prosthetic limb into which the amputee places his or her residual limb (stump).